Motor vehicle traffic has continued to increase for numerous years and this increase has not always been followed, in some regions, by a suitable improvement in the road network. This means that in some circumstances, jams occur which undoubtedly hinder traffic flow. It has therefore been thought that it should be possible to remedy these drawbacks by monitoring vehicle traffic.
In order to perform this type of monitoring, it is necessary to provide sensors capable of giving an image of vehicle traffic. Numerous sensors have been developed. For example, a sensor has been devised based on light rays which are directed towards the paths along which the vehicles run. Light sensitive receivers are associated with these light rays as generally returned by reflecting surfaces disposed for this purpose on the roadway, with the receivers delivering traffic-representative signals at their outputs each time a vehicle interrupts these light beams.
This technique gives good results. However, the signals delivered are representative of traffic at one point only and the sensors used are not flexible in operation since they require items to be placed on the roadway. They must therefore be located in defined positions and they cannot be moved without giving rise to difficulties. Further, the elements disposed on the roadway need frequent attention, if only to clean their reflecting surfaces.
Other sensors have been made for increasing the area under surveillance. This applies to a sensor constituted by a magnetic loop embedded in the roadway. Such a sensor mitigates the above-mentioned drawbacks to some extent, but its use still remains too localized and it is always related to a given position on the roadway.
Thus, the present invention seeks to implement a method of determining the trajectory of a body such as a motor vehicle, for example, on a portion of a path, thereby making it possible to monitor a larger area of the path without requiring special additions to the portion of the path under surveillance, and which is capable of giving a plurality of results defining all the parameters of given traffic, e.g. motor vehicle traffic.
The present invention also seeks to provide apparatus for implementing a method.